title: Extremely sensitive and selective NO probe based on villi-like WO3 nanostructures for application to exhaled breath analyzers.
abstract: Self-assembled WO3 thin film nanostructures with 1-dimensional villi-like nanofingers (VLNF) have been synthesized on the SiO2/Si substrate with Pt interdigitated electrodes using glancing angle deposition (GAD). Room-temperature deposition of WO3 by GAD resulted in anisotropic nanostructures with large aspect ratio and porosity having a relative surface area, which is about 32 times larger than that of a plain WO3 film. A WO3 VLNF sensor shows extremely high response to nitric oxide (NO) at 200 °C in 80% of relative humidity atmosphere, while responses of the sensor to ethanol, acetone, ammonia, and carbon monoxide are negligible. Such high sensitivity and selectivity to NO are attributed to the highly efficient modualtion of potential barriers at narrow necks between individual WO3 VLNF and the intrinsically high sensitivity of WO3 to NO. The theoretical detection limit of the sensor for NO is expected to be as low as 88 parts per trillion (ppt). Since NO is an approved biomarker of chronic airway inflammation in asthma, unprecedentedly high response and selectivity, and ppt-level detection limit to NO under highly humid environment demonstrate the great potential of the WO3 VLNF for use in high performance breath analyzers.
authors.affiliation: Electronic Materials Research Center, Korea Institute of Science and Technology , Seoul 136-791, Republic of Korea.
authors.forename: Hi Gyu
authors.initials: HG
authors.lastname: Moon
authors.forename: You Rim
authors.initials: YR
authors.lastname: Choi
authors.forename: Young-Seok
authors.initials: YS
authors.lastname: Shim
authors.forename: Kwon-Il
authors.initials: KI
authors.lastname: Choi
authors.forename: Jong-Heun
authors.initials: JH
authors.lastname: Lee
authors.forename: Jin-Sang
authors.initials: JS
authors.lastname: Kim
authors.forename: Seok-Jin
authors.initials: SJ
authors.lastname: Yoon
authors.forename: Hyung-Ho
authors.initials: HH
authors.lastname: Park
authors.forename: Chong-Yun
authors.initials: CY
authors.lastname: Kang
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Jang
mesh_terms: D001944:Breath Tests / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D049329:Nanostructures / Q000737:chemistry*; D009569:Nitric Oxide / Q000302:isolation & purification* / Q000378:metabolism; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D014414:Tungsten / Q000737:chemistry*
chemical_list: D010087:Oxides; D009569:Nitric Oxide; D012822:Silicon Dioxide; C511604:tungsten oxide; D014414:Tungsten